Field of the Invention
This invention relates generally to commercial and residential turf irrigation systems, and more particularly to an improved, microprocessor-based irrigation system for monitoring soil conditions in a plurality of zones and for controlling the flow of water to the different zones on an "as needed" basis. The microprocessor-based controller of the present invention is also highly flexible and easy to program because of the interactive software incorporated.
Discussion of the Prior Art
A rather wide variety of underground sprinkling systems are available in the marketplace and are described in the patent literature in which water, under pressure, is made to flow through a plurality of branches leading to different zones comprising the area to be irrigated under control of solenoid operated water valves. A water valve, when energized, permits water to flow through one or more spray heads in a given zone in an attempt to uniformly distribute the water over that particular zone. Individual zones are generally watered sequentially so that an undue drop in water pressure is not encountered as would be the case if all spray heads in all zones are fed simultaneously. In accordance with the prior art, the controller for overseeing the turn-on and turn-off of the respective solenoid valves includes a plurality of timing mechanisms, one being for initiating the turn-on of the system at preprogrammed watering days and at a particular time on such watering days. Further timing means are provided for each of the zones which can be set to determine the length of time that the solenoid valve associated with that zone will remain on. In the simplest of systems, the watering day/water time timing device is an alternating current synchronous motor driving a cam that cooperates with electrical switches.
Programming is accomplished by selectively displacing manually positionable pins on a control panel for setting the watering day and time on the selected watering days when irrigation is to begin. The length of time that any given solenoid valve for a particular zone is actuated is controlled by a further electronic timer. Typical of the above-described systems is that supplied by the Toro Company of Minneapolis, Minn., and which is described in the Bancroft Patent 5,060,859.
A more technically advanced irrigation control system is described in the Krause et al. Patent 5,038,268. In accordance with this patent, the controller comprises a microcomputer having a keyboard and a display for controlling up to sixteen watering stations. The microprocessor is adapted to receive control signals from moisture sensors in each of the zones as well as from a flow meter used to measure the cumulative flow through all of the branches whereby the amount of water distributed is either a precomputed time interval or a lesser interval as determined by the output from the moisture sensor for the zone in question. The system of the Krause et al. '268 patent involves a rather complicated keyboard having three keys per station for establishing an off-mode, an on-mode and an auto-mode for each such station. The keyboard also incorporates a numerical display for providing the operator with an indication of previously programmed start and stop times as well as fault messages used in trouble-shooting. There is no interaction between the display and the keyboard for facilitating the programming of the multiple valves used in a multi-zone system.
There is a need in the residential/commercial irrigation industry for an irrigation controller that responds to soil moisture sensors in individual zones as a way of conserving water. An ideal controller should be "user friendly", i.e., easy to program and requiring a minimum number of keys or push-buttons to operate the controller. It should also allow irrigation to take place in zones where watering is required, while bypassing zones where adequate soil moisture is indicated- To add flexibility, it should be possible to selectively deactivate any of the moisture sensors to thereby override the modification to the controller performance caused by sensor inputs. Moreover, the system should be easy to trouble shoot in the event of faults in any of the plurality of zones.